The phrase "a joint demonstration" is correct and usable in written English.
It can be used when referring to a collaborative event or protest involving multiple parties or organizations.
Example: "The community organized a joint demonstration to advocate for environmental protection and climate action."
Alternatives: "a collaborative protest" or "a united demonstration".
The impact of a joint demonstration by supporters known for their fierce animosity towards each other would be bound to generate fresh headlines around the world.
The Anti-Nazi League - which had formed in 1977 - were keen to hold a joint demonstration with RAR in the spring of 1978 to encourage supporters to vote against the National Front in May's council elections.
A joint demonstration of Occupy activists and telephone workers is planned for Friday to target Verizon, and Occupy organizers say more unions are reaching out to a newly formed labor relations committee to ask for help in planning future actions.
1937 Nazis Threaten Demonstration LONDON — Great Britain and France flatly refused tonight [June 22] to participate with Germany and Italy in a joint naval demonstration off the coast of Valencia in reply to the alleged attempts by the Valencia government submarines to torpedo the German cruiser Leipzig near Oran, Algeria, last week.
Innovative method development by young researchers at universities, research centres and private companies is interlinked with a joint European demonstration programme and higher tier EDA, and extensive training courses.
Innovative method development by young researchers at major European universities, research centers, and private companies has been closely interlinked with a joint European demonstration program, higher-tier EDA, and specialized training courses and secondments.
Instead, he says, "... it took a group of around 70 women and children yesterday to hold the first joint demonstration condemning the brutal murders..
The major aim of this joint demonstration project is to create documentation of cuneiform tablets for application in research.
The State Grid Corporation of China (SGCC) is building the national wind/PV/BESS and transmission joint demonstration project and it is located in the region of Zhangbei, Hebei, China.
Their joint demonstration of the depth of the anti-trade constituency is likely to have a lasting effect even if neither candidate makes it all the way to the presidency.
There were even times (when they weren't killing each other in the streets) that they held joint demonstrations.
